thanks.. makes sense.. as also takes care of the 'color' problem (as I can use a resistor to match that specific led's vF

re: wiring

I have +Vin (PSU +).. going to breadboard.. same row, next hole.. I have resistor (470 Ohm), in-line/same row after that second resistor leg (again same row).. I have the +Vout going to Arduino A5 pin.

still (same row) after the Vout to A5.. I have (last hole in row) 1 leg of resistor (1k Ohm)..going to another , new row.

In new row.. on 1 side of resistor.. I have -Vin lead (goes to PSU -).. on other side of resistor (same 1K Ohm) I have the -Vout to a GND pin on the Arduino

here is a different schematic.. more or less showing it how it is on the breadboard.. (maybe because Im using a BB I screwed it up?) (yes, I know you dont like breadboards.. its all I have!) LOL

Also.. can you dumb this up a bit? LOL.. or maybe give an explanation?

Quote

although a volt meter with an input impedance of 1K5 is a bit of a poor meter.

Im not sure what you mean? in any project "I" would use this in would be a 3.7v, 4.5v, 6v or 7.4 volt (the only battery packs I really use in my hobby).. mostly 7.4v Li-Ions.. but others have been used.

I want to light ALL leds if full juice.. and go down on the number of leds lit after that.. (reaching my cut-off/threshold)...which would leave the leds only 1 lit.

"input impedance of 1K5 " just means your meter draws a lot of current - in this 7.4V/1500 = 5mA, could use 4.7K.10K and cut that down to 0.5mA.

7.4 to 470, to 1K to gnd. Junction of 470/1K should be 5.03V if batteries were discharged and down at 3.7V. (7.4*1K)/(.47K + 1K)Fresh batteries will be more like 8.4V tho, so 5.71V, dropping to ~5V when discharged.Consider changing your R values to reflect that.

scottydb4b

Hi, I have a problem also with a arduino voltmeter/ammeter that is part of a power supply I made.I have written all the code connected it up and it reads the volts and amps pretty accurately on an lcd.My problem is when i connect a load to the power supply the voltage drop shown on the lcd is no where near what it reads on a multimeter. ie. if I set the voltage to say 6.00 volts connect a 3.9ohm load the lcd shows 5.8 volts where as the multimeter shows something around 5.00 volts. and doesn't drop much more with bigger loads either.Does anyone know why this might be?